WO2021074879A1 - Composition de mfc avec des fibres de cellulose phosphorylées - Google Patents

Composition de mfc avec des fibres de cellulose phosphorylées Download PDF

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Publication number
WO2021074879A1
WO2021074879A1 PCT/IB2020/059762 IB2020059762W WO2021074879A1 WO 2021074879 A1 WO2021074879 A1 WO 2021074879A1 IB 2020059762 W IB2020059762 W IB 2020059762W WO 2021074879 A1 WO2021074879 A1 WO 2021074879A1
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mfc
range
composition
film
cellulose fibers
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PCT/IB2020/059762
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English (en)
Inventor
Kaj Backfolk
Isto Heiskanen
Katja LYYTIKÄINEN
Gisela CUNHA
Otto NYLEN
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Stora Enso Oyj
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Publication of WO2021074879A1 publication Critical patent/WO2021074879A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
    • C08B5/00—Preparation of cellulose esters of inorganic acids, e.g. phosphates
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
    • C08L1/02—Cellulose; Modified cellulose
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
    • C08L1/08—Cellulose derivatives
    • C08L1/16—Esters of inorganic acids
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D101/00—Coating compositions based on cellulose, modified cellulose, or cellulose derivatives
    • C09D101/02—Cellulose; Modified cellulose
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
    • D21H11/18—Highly hydrated, swollen or fibrillatable fibres
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
    • D21H11/20—Chemically or biochemically modified fibres
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/03—Non-macromolecular organic compounds
    • D21H17/05—Non-macromolecular organic compounds containing elements other than carbon and hydrogen only
    • D21H17/10—Phosphorus-containing compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
    • C08J2301/02—Cellulose; Modified cellulose
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2401/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
    • C08J2401/08—Cellulose derivatives
    • C08J2401/16—Esters of inorganic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/20—Manufacture of shaped structures of ion-exchange resins
    • C08J5/22—Films, membranes or diaphragms
    • C08J5/2206—Films, membranes or diaphragms based on organic and/or inorganic macromolecular compounds
    • C08J5/2212—Natural macromolecular compounds

Definitions

  • the present disclosure relates to microfibrillated cellulose (MFC) compositions for preparation of transparent or translucent films useful, for example, as gas and/or grease barrier films in paper and paperboard.
  • MFC microfibrillated cellulose
  • the present invention further relates to multilayer materials comprising such MFC compositions and to methods for manufacturing such MFC compositions. Background
  • Nanocellulosic films have emerged as an interesting alternative to conventional gas barrier films, such as aluminum and synthetic polymer films and various laminates thereof.
  • Nanocellulosic films have been developed, in which cellulosic fibrils have been dispersed and/or suspended in aqueous media and thereafter re-organized and rebonded together to form a dense film with high barrier properties.
  • the MFC films and coatings are also inherently transparent or translucent to visible light, making them especially useful in applications where transparency or translucency of the film in the visible light spectrum (typically in the range of 380 to 740 nm) is required.
  • An MFC coatings may for example be used as a varnish or overlay varnish.
  • MFC films can be made by applying an MFC suspension on a porous substrate, for example a membrane or wire, forming a web followed by dewatering of the web by draining water through the substrate to form the film. This can be accomplished e.g. by use of a paper- or paperboard machine type of process.
  • US2012298319A teaches a method of manufacturing of an MFC film by applying a furnish comprising MFC directly on porous substrate thus allowing the MFC to be dewatered and filtered.
  • the film can be made by use of casting technologies, including applying an MFC dispersion onto a non-porous cast substrate, such as a polymeric or metal substrate, and drying said film by evaporation and/or wet pressing. Films made by casting technologies usually provide a more uniform thickness distribution and a smoother surface.
  • the publication EP2771390 A4 describes preparation of MFC films, in which an aqueous cellulose nanofiber dispersion is coated on a paper or polymeric substrate, dried and finally peeled off as a nanofiber film sheet.
  • MFC films may be brittle and provide low strain ability and tear resistance since the fiber network formed from short fibers will not have the ability to stretch in the same way as longer fibers.
  • the film When forming MFC films of low grammage and thickness, the film may easily break during wet web forming, converting or handling. Also, the gas barrier properties of such MFC films tend to deteriorate at high temperatures and high humidity.
  • MFC is a relatively expensive material, making the cost of pure MFC films high.
  • Various additives have been considered in order to address the problems associated with improving the mechanical properties of MFC films. Flowever, while the use of a given additive may solve one specific problem, it may not be able to solve or maintain other physical or mechanical requirements and may even cause new problems.
  • the addition of longer cellulose fibers in the MFC films may improve the mechanical properties of the films but will at the same time impair the gas barrier properties and transparency or translucency of the film.
  • Other additives may adversely affect the re-use of the material such as in the form of broke or pre- or post-consumer reject.
  • MFC microfibrillated cellulose
  • MFC microfibrillated cellulose
  • phosphorylated cellulose fibers can be added to an MFC composition to improve the mechanical properties of MFC films formed from the composition, while still maintaining the good transparency or translucency and good gas barrier properties characteristic to MFC films without added fibers.
  • the improved mechanical properties of MFC films with phosphorylated cellulose fibers may at least in part be derived from the anionic nature and functional groups of the fibers providing an increased reactivity and number of sites for cross-linking.
  • a microfibrillated cellulose (MFC) composition for preparation of transparent or translucent films or coatings, said composition comprising:
  • MFC at a concentration in the range of 50-99.9 wt%
  • phosphorylated cellulose fibers at a concentration in the range of 0.1-50 wt%, based on the total dry weight of the MFC composition.
  • the composition may be in the form of a solid composition, e.g. in the form of a dried or substantially dried film, coating or powder, or it can be in the form of a dispersion in a liquid medium, preferably water.
  • a composition in the form of a dispersion can be used for the preparation of a film or coating.
  • the composition is a solid composition.
  • the solid composition preferably has a moisture content of 20 wt% or less, preferably 15 wt% or less, more preferably 10 wt% or less.
  • the MFC composition is a dispersion, preferably an aqueous dispersion.
  • the consistency of the dispersion is preferably in the range of 0.1-50 wt%, preferably in the range of 0.2-30 wt%, and more preferably in the range of 0.3-20 wt%.
  • the drainability of the MFC composition will depend on the type and amount of MFC and the phosphorylated cellulose fibers used, as well as other components added to the composition.
  • the MFC composition has a Schopper-Riegler (SR) number > 20, preferably > 30, and more preferably > 40, as measured according to the standard ISO 5267-1.
  • SR Schopper-Riegler
  • the MFC composition may be comprised solely of a mixture of MFC and phosphorylated cellulose fibers, or it can comprise the mixture of MFC and phosphorylated cellulose fibers combined with other ingredients or additives.
  • the MFC composition preferably includes MFC as its main component based on the total dry weight of the MFC composition. Specifically, the MFC composition comprises MFC at a concentration in the range of 50-99.9 wt%. In some embodiments, the MFC composition comprises in the range of 50-99.5 wt%, preferably in the range of 60-99.5 wt%, more preferably in the range of 65-98 wt% of MFC, based on the total dry weight of the MFC composition.
  • Microfibrillated cellulose shall in the context of the patent application be understood to mean a nano scale cellulose particle fiber or fibril with at least one dimension less than 1000 nm.
  • MFC comprises partly or totally fibrillated cellulose or lignocellulose fibers.
  • the liberated fibrils have an average diameter less than 1000 nm, whereas the actual fibril diameter or particle size distribution and/or aspect ratio (length/width) depends on the source and the manufacturing methods.
  • the length of the fibrils can vary from around 1 to more than 10 micrometers.
  • a coarse MFC grade might contain a substantial fraction of fibrillated fibers, i.e. protruding fibrils from the tracheid (cellulose fiber), and with a certain amount of fibrils liberated from the tracheid (cellulose fiber).
  • the MFC comprises less than 50 wt%, preferably less than 30 wt%, and more preferably less than 20 wt%, of MFC fibers having a diameter above 1000 nm.
  • the MFC comprises less than 10 wt%, preferably below 7.5 wt%, more preferably below 5 wt%, of fibers having a length of > 0.2 mm, as measured using an FS5 optical fiber analyzer (Valmet).
  • MFC cellulose microfibrils, fibrillated cellulose, nanocellulose, nanofibrillated cellulose, fibril aggregates, nanoscale cellulose fibrils, cellulose nanofibers, cellulose nanofibrils, cellulose microfibers, cellulose fibrils, microfibrillar cellulose, microfibril aggregates and cellulose microfibril aggregates.
  • the cellulose fiber is preferably fibrillated to such an extent that the final specific surface area of the formed MFC is from about 1 to about 400 m 2 /g, or more preferably 50-300 m 2 /g when determined for a solvent exchanged and freeze-dried material with the Nitrogen sorption (BET) method.
  • MFC multi-pass refining
  • pre- hydrolysis followed by refining or high shear disintegration or liberation of fibrils.
  • One or several pre-treatment steps are usually required in order to make MFC manufacturing both energy efficient and sustainable.
  • the cellulose fibers of the pulp to be utilized may thus be pre-treated, for example enzymatically or chemically, to hydrolyse or swell the fibers or to reduce the quantity of hemicellulose or lignin.
  • the cellulose fibers may be chemically modified before fibrillation, such that the cellulose molecules contain other (or more) functional groups than found in the native cellulose.
  • Such groups include, among others, carboxymethyl (CMC), aldehyde and/or carboxyl groups (cellulose obtained by N- oxyl mediated oxidation, for example "TEMPO”), or quaternary ammonium (cationic cellulose). After being modified or oxidized in one of the above-described methods, it is easier to disintegrate the fibers into MFC or nanofibrils.
  • CMC carboxymethyl
  • TEMPO N- oxyl mediated oxidation
  • quaternary ammonium cationic cellulose
  • the nanofibrillar cellulose may contain some hemicelluloses, the amount of which is dependent on the plant source.
  • Mechanical disintegration of the pre-treated fibers, e.g. hydrolysed, pre-swelled, or oxidized cellulose raw material is carried out with suitable equipment such as a refiner, grinder, homogenizer, colloider, friction grinder, ultrasound sonicator, fluidizer such as microfluidizer, macrofluidizer or fluidizer-type homogenizer.
  • suitable equipment such as a refiner, grinder, homogenizer, colloider, friction grinder, ultrasound sonicator, fluidizer such as microfluidizer, macrofluidizer or fluidizer-type homogenizer.
  • the product might also contain fines, or nanocrystalline cellulose, or other chemicals present in wood fibers or in papermaking process.
  • the product might also contain various amounts of micron size fiber particles that have not been efficiently fibrillated.
  • MFC is produced from wood cellulose fibers, both from hardwood or softwood fibers. It can also be made from microbial sources, agricultural fibers such as wheat straw pulp, bamboo, bagasse, or other non-wood fiber sources. It is preferably made from pulp including pulp from virgin fiber, e.g. mechanical, chemical and/or thermomechanical pulps. It can also be made from broke or recycled paper.
  • the MFC of the MFC composition may be unmodified MFC or chemically modified MFC, or a mixture thereof. In some embodiments, the MFC is an unmodified MFC. Unmodified MFC refers to MFC made of unmodified or native cellulose fibers.
  • the unmodified MFC may be a single type of MFC, or it can comprise a mixture of two or more types of MFC, differing e.g. in the choice of cellulose raw material or manufacturing method.
  • Chemically modified MFC refers to MFC made of cellulose fibers that have undergone chemical modification before, during or after fibrillation.
  • the MFC is a chemically modified MFC.
  • the chemically modified MFC may be a single type of chemically modified MFC, or it can comprise a mixture of two or more types of chemically modified MFC, differing e.g. in the type of chemical modification, the choice of cellulose raw material or the manufacturing method.
  • the MFC of the MFC composition has a Schopper-Riegler (SR) number > 70, preferably > 80, and more preferably > 90, as measured according to the standard ISO 5267-1.
  • SR Schopper-Riegler
  • the MFC composition comprises phosphorylated cellulose fibers at a concentration in the range of 0.1-50 wt%. In some embodiments, the MFC composition comprises in the range of 0.1-30 wt%, preferably in the range of 0.5- 20 wt%, more preferably in the range of 1-10 wt% of phosphorylated cellulose fibers, based on the total dry weight of the MFC composition.
  • the phosphorylated cellulose fibers may for example be phosphorylated cellulose fibers obtained from hardwood or softwood.
  • the phosphorylated cellulose fibers may be phosphorylated fibers obtained from chemical, mechanical or chemimechanical pulp, such as kraft pulp or dissolving pulp.
  • the phosphorylated cellulose fibers are larger than the microfibrils of the MFC.
  • the MFC is typically made up of cellulose particle fibers or fibrils with at least one dimension in the range of 1-1000 nm and often less than 100 nm.
  • the phosphorylated cellulose fibers of the MFC composition preferably have an average fiber diameter (fiber width) above 1000 nm.
  • the size of the phosphorylated cellulose fibers may depend on the source of the fibers, e.g. hardwood, softwood and the pulp source.
  • the phosphorylated cellulose fibers of the MFC composition have a fiber width of more than 5 pm, preferably more than 10 pm, as measured using an FS5 optical fiber analyzer (Valmet).
  • the phosphorylated cellulose fibers of the MFC composition preferably have a length-weighted mean fiber length above 0.5 mm, i.e. above 500000 nm.
  • the phosphorylated cellulose fibers have a length-weighted mean fiber length (Lc(l)) of more than 0.2 mm and preferably more than 0.5 mm (as measured according to the standard ISO 16065-2).
  • the phosphorylated cellulose fibers of the MFC composition have a length-weighted mean fiber length in the range of 0.2-4 mm, preferably in the range of 0.3-2 mm, more preferably in the range of 0.5-2 mm.
  • Length-weighted mean fiber length as used herein refers to the length-weighted mean fiber length (Lc(l)) measured according to the standard ISO 16065-2 using an FS5 optical fiber analyzer (Valmet).
  • the phosphorylated cellulose fibers of the MFC composition comprise less than 10 wt%, preferably below 7.5 wt%, more preferably below 5 wt%, of fibers having a length in the range of ⁇ 0.2 mm, as measured using an FS5 optical fiber analyzer (Valmet).
  • the phosphorylated cellulose fibers include cellulose fibers or fragments of cellulose fibers or a mixture thereof, in which at least a portion of the hydroxyl groups have been chemically modified by phosphorylation.
  • the phosphorylated cellulose fibers have a degree of phosphorylation of 0.1 mmol/g or higher, preferably 0.3 mmol/g or higher.
  • Phosphorylated pulp or phosphorylated cellulose fibers can for example be obtained by reacting a pulp of cellulose fibers soaked in a solution of NH4H2PO4, water and urea and optionally neutralizing and washing the phosphorylated pulp.
  • the pulp should not be subjected to mechanical disintegration which leads high degree of fibrillation. Mixing and gentle shear can be applied on the suspension in order to create a homogenous suspension.
  • suitable phosphorylating agents include phosphoric acid, phosphorus pentaoxide, phosphorus oxychloride, diammonium hydrogen phosphate and sodium dihydrogen phosphate.
  • phosphorylated pulp In the reaction to form phosphorylated pulp, alcohol functionalities (-OH) in the cellulose are converted to phosphate groups (-OPO3 2' ). In this manner, crosslinkable functional groups (phosphate groups) are introduced to the pulp fibers.
  • the phosphorylated pulp is in the form of its sodium salt.
  • Phosphorylated pulp or phosphorylated cellulose fibers can be tailored with different degree of substitution. In some embodiments, the degree of substitution is in the range of 0.1 -4.0, preferably in the range of 0.2 - 3.8, more preferably in the range of 0.3-3.0, or most preferably in the range of 0.4 to 2.0 mmol/g of phosphate groups as measured by a titration method or by using elemental analysis described in the prior art.
  • the phosphorylated fibers are preferably washed but the present inventors have found that relatively high amounts of residual chemicals or salts or impurities from the manufacturing process can be present in the material without significant adverse effects on the barrier properties or the optical or mechanical properties.
  • the purity of phosphorylated cellulose fibers may typically be in the range of 50- 100%, wherein the remaining portion may include salts or electrolytes or neutralization or washing chemicals from the phosphorylation process, as well as dissolved hemicellulose.
  • the phosphorylated fibers can also be phosphorylated pulp or a reject fraction from a phosphorylated fiber fibrillation plant.
  • the phosphorylated cellulose fibers used in the MFC composition have a Schopper-Riegler (SR) number ⁇ 80, preferably ⁇ 60, and more preferably ⁇ 40, as measured according to the standard ISO 5267-1. These values refer to the phosphorylated fibers as such or the actual fiber content of the phosphorylated pulp. Preferably, the SR value is determined for a washed fraction
  • the formulation of the MFC composition may vary depending on the intended use of the MFC composition and on the intended mode of application or formation of a film or coating of the MFC composition.
  • the MFC composition may include a wide range of ingredients in varying quantities to improve the end performance of a film or coating of the MFC composition.
  • the MFC composition further comprises a metal salt.
  • a metal salt may assist crosslinking of the phosphorylated fibers, further improving the mechanical properties of coatings or films formed of the MFC composition.
  • the metal salt may preferably be added during or after coating or film formation.
  • the MFC composition may further comprise additives such as starch, fillers, retention aids, flocculation additives, deflocculating additives, dry strength additives, softeners, lubricants, wet strength agents, colorants or dyes, defoamers, fixatives, biocides, pH regulators, UV blocking agents, or mixtures thereof.
  • additives such as starch, fillers, retention aids, flocculation additives, deflocculating additives, dry strength additives, softeners, lubricants, wet strength agents, colorants or dyes, defoamers, fixatives, biocides, pH regulators, UV blocking agents, or mixtures thereof.
  • the MFC composition may for example comprise additives that will improve different properties of the MFC composition and/or a film or coating formed thereof, such as latex and/or polyvinyl alcohol (PVOFI) for enhancing the ductility of the coating.
  • PVOFI polyvinyl alcohol
  • the MFC composition further comprises a water-soluble polymer selected from the group consisting of a starch, a polyvinyl alcohol (PVOFI), a cellulose derivative, a hemicellulose, a polyacrylamide, a polydiallyldimethylarnmonium chloride (PDADMAC), a polyvinylamine (PVAm), a polyethyleneimine (PEI), a protein or a mixture thereof, preferably a PVOFI.
  • a water-soluble polymer selected from the group consisting of a starch, a polyvinyl alcohol (PVOFI), a cellulose derivative, a hemicellulose, a polyacrylamide, a polydiallyldimethylarnmonium chloride (PDADMAC), a polyvinylamine (PVAm), a polyethyleneimine (PEI), a protein or a mixture thereof, preferably a PVOFI.
  • PVOFI polyvinyl alcohol
  • PVAm polyvinylamine
  • PEI polyethyleneimine
  • the water-soluble polymer is a PVOFI.
  • the PVOFI may be a single type of PVOFI, or it can comprise a mixture of two or more types of PVOFI, differing e.g. in degree of hydrolysis or viscosity or different functional groups.
  • the PVOFI may for example have a degree of hydrolysis in the range of 80-99 mol%, preferably in the range of 88-99 mol%.
  • the PVOFI may preferably have a viscosity above 5 mPaxs in a 4 % aqueous solution at 20 °C as measured according to the standard DIN 53015 / JIS K6726.
  • the MFC composition comprises in the range of 0.1-20 wt%, preferably in the range of 0.5-15 wt%, more preferably in the range of 1-10 wt% of the water-soluble polymer, based on the total dry weight of the MFC composition.
  • the MFC composition further comprises a pigment.
  • the pigment may for example comprise inorganic particles of talcum, silicates, carbonates, alkaline earth metal carbonates and ammonium carbonate, or oxides, such as transition metal oxides and other metal oxides.
  • the pigment may also comprise nano-size pigments such as nanoclays and nanoparticles of layered mineral silicates, for instance selected from the group comprising montmorillonite, bentonite, kaolinite, hectorite and hallyosite.
  • the particle size and the concentration of the pigments should preferably be low.
  • the pigment is selected from the group consisting of nanoclays and nanoparticles of layered mineral silicates, more preferably bentonite.
  • the MFC composition comprises in the range of 0.1-20 wt%, preferably in the range of 0.5-15 wt%, more preferably in the range of 1-10 wt% of the pigment, based on the total dry weight of the MFC composition.
  • the MFC composition of the first aspect described above is useful in the preparation of MFC films, particularly transparent or translucent MFC films.
  • an MFC film comprising an MFC composition as described above with reference to the first aspect.
  • the MFC film may be a free standing MFC film, an MFC coating on a substrate, or an MFC layer of a multilayer material.
  • the film may for example be prepared by casting, coating or wet laid process.
  • the MFC film has a grammage in the range of 10-100 gsm, preferably in the range of 12-50 gsm, more preferably in the range of 15-40 gsm.
  • a coating can have a grammage in the range of 1-20 gsm, or more preferably in the range of 1-10 gsm.
  • the MFC film has a tear index at least 5% higher, preferably at least 10% higher, more preferably at least 15% higher, than the tear index of a corresponding film without the phosphorylated cellulose fibers, as measured according to the standard ISO 1974.
  • the MFC film has an oxygen transfer rate (OTR), as measured according to the standard ASTM F-1927-98 at 50% relative humidity and 23 °C, of less than 30 cc/m 2 /24h/atm, and preferably less than 20 cc/m 2 /24h/atm.
  • OTR oxygen transfer rate
  • the MFC film has a transparency of at least 75%, preferably at least 80%, as measured according to the standard DIN 53147.
  • the MFC films or coatings are often used as a barrier layer in a multilayer material, such as a paper or paperboard comprised of two or more plies.
  • a multilayer material comprising at least: a substrate layer and an MFC layer comprising an MFC composition as described above with reference to the first aspect.
  • the MFC layer is an MFC film as described above with reference to the second aspect.
  • the MFC layer may be attached to the substrate layer directly, or via one or more intermediate layers.
  • the MFC layer may be coated or wet laid directly onto the substrate layer, or an MFC film may be laminated to the substrate layer using an intermediate adhesive layer.
  • the substrate layer is paper or paperboard.
  • the paper or paperboard has a basis weight in the range of 20-500 gsm (g/m 2 ), preferably in the range of 80-400 gsm.
  • the multilayer material is a paper or paperboard comprised of two or more plies, wherein at least one ply comprises an MFC composition as described above with reference to the first aspect.
  • the at least one ply comprising an MFC composition is an MFC film as described above with reference to the second aspect.
  • the multilayer material comprises one or more heat sealable layers, such as one or more polyethylene layers.
  • a method of preparing an MFC film comprising: a) preparing an aqueous MFC composition as described above with reference to the first aspect; b) forming a film of the aqueous MFC composition; and c) allowing the film to dry to obtain the MFC film.
  • the aqueous MFC composition may be prepared in a number of different ways.
  • the aqueous MFC composition may for example be prepared by mixing dry MFC and dry phosphorylated cellulose fibers and dispersing the dry mixture in water, or by adding phosphorylated cellulose fibers, e.g. in the form of phosphorylated cellulose pulp, to an aqueous MFC dispersion, preferably a high consistency MFC dispersion.
  • the phosphorylated cellulose fibers, e.g. in the form of phosphorylated cellulose pulp can be added dry or in high consistency form.
  • High consistency form means that the consistency of the pulp is higher than 5 wt% preferably higher than 10 wt%, and more preferably higher than 15 wt%.
  • the step a) comprises mixing MFC having a Schopper-Riegler (SR) number > 70, preferably > 80, and more preferably > 90, as measured according to the standard ISO 5267-1, with phosphorylated cellulose fibers having a Schopper-Riegler (SR) number ⁇ 80, preferably ⁇ 60, and more preferably ⁇ 40, as measured according to the standard ISO 5267-1.
  • the drying in step c) is performed at a temperature above 50 °C, preferably above 70 °C, more preferably above 90 °C.
  • the drying temperature refers to the temperature in the film.
  • the drying source might may have a much higher temperature than the actual film.
  • Drying at elevated temperature may assist crosslinking of the phosphorylated fibers, further improving the mechanical properties of coatings or films formed of the MFC composition. Drying means that solid content of the MFC film is at least 80 wt%, preferably at least 85 wt% and more preferably at least 90% after the drying.
  • phosphorylated cellulose fibers can be used to improve the mechanical properties of MFC films, while still maintaining the good transparency or translucency and good gas barrier properties characteristic to MFC films without added fibers.
  • phosphorylated cellulose fibers as a strength enhancement agent in an MFC composition for preparation of transparent or translucent films or coatings.
  • the phosphorylated cellulose fibers preferably have an average fiber diameter (fiber width) above 1000 nm.
  • the phosphorylated cellulose fibers of the MFC composition have a fiber width of more than 5 pm, preferably more than 10 pm, as measured using an FS5 optical fiber analyzer (Valmet).
  • the phosphorylated cellulose fibers preferably have a length-weighted mean fiber length above 0.5 mm, i.e. above 500000 nm. In some embodiments, the phosphorylated cellulose fibers have a length-weighted mean fiber length in the range of 0.2-4 mm, preferably in the range of 0.3-2 mm, more preferably in the range of 0.5-2 mm.
  • Length-weighted mean fiber length as used herein refers to the length-weighted mean fiber length (Lc(l)) as measured according to the standard 16065-2 using an FS5 optical fiber analyzer (Valmet).
  • the phosphorylated cellulose fibers include cellulose fibers or fragments of cellulose fibers or a mixture thereof, in which at least a portion of the hydroxyl groups have been chemically modified by phosphorylation.
  • the phosphorylated cellulose fibers have a degree of phosphorylation of 0.1 mmol/g or higher, preferably 0.3 mmol/g or higher.
  • the phosphorylated cellulose fibers have a Schopper- Riegler (SR) number ⁇ 80, preferably ⁇ 60, and more preferably ⁇ 40, as measured according to the standard ISO 5267-1.
  • SR Schopper- Riegler
  • the MFC composition of the fifth aspect is an MFC composition as described above with reference to the first aspect.
  • wt% refers to weight percent based on the total dry weight of the composition.
  • composition refers to weight percentage of dry solid substances in the composition based on the total weight of the composition.
  • Microfibri Hated cellulose (MFC):
  • microfibri Hated cellulose used in the experiments was prepared from pre- treated pine kraft pulp and obtained through mechanical disintegration using a microfluidizer. The sample was run through the microfluidizer 3 times, using 2 passes through 400 and 200 micron chambers and 1 pass through 200 and 100 micron chambers.
  • Kraft pulp fibers were treated with a mixture of phosphoric acid, urea and water (Table 1). The treated fibers were then dried at 80 °C until the moisture content was below 1%. The phosphorylation reaction was conducted by increasing the temperature to 150 °C and allowing the treated fibers to react for 10 min.
  • the phosphorylated pulp fibers (referred to herein as unwashed (UW) phosphorylated pulp fibers) were subsequently dispersed in distilled water and washed in a porous fabric. The washed pulp was then re-dispersed in distilled water and the pH was adjusted to 12.5 with 50% NaOH and thereafter re-washed until pH was below 10.
  • the phosphorylated pulp was subsequently allowed to drain inside the porous fabric to obtain a dry matter content of ca. 10%.
  • the degree of substitution (DS) was determined by acid titration. Table 1. Conditions used to prepare the different phosphorylated pulp fibers and respective degree of substitution (DS) as determined by acid titration and fiber properties.
  • the MFC can be characterized with different means.
  • One way to estimate the particle size dimension is by laser diffraction. By using high resolution microscope such as Scanning Electron Microscope, it is possible to evaluate the thickness and thickness distribution.
  • Another method to estimate MFC fineness is to determine the drainage resistance using the Schopper-Riegler method according to the standard ISO 5267-1.
  • the SR value of the unwashed phosphorylated fibers were 11 measured according to ISO 5267-1 and the SR value of the low DS phosphorylated pulp were 11.5 measured according to ISO 5267-1.
  • the oxygen barrier properties of the films were measured according to the standard ASTM F 1927-98 at 50% RH and 23 °C.
  • the water vapor barrier properties were measured according to the standard ASTM F 1249-90 at 50 % RH and 23 °C.
  • the optical properties of the films were determined according to the standard ASTM D1003-13 which measures the haze and luminous transmittance of transparent materials.
  • the total light transmittance of the films was determined using Cary 100 UV/VIS spectrophotometer with DRA CA301 Integrating Sphere in the transmission port in the wavelength area of 200-890 nm.
  • the transparency of the films was determined according to the standard DIN 53147.
  • the determination of the tensile strength properties was done according to the standard ISO 1924 with the exception that the draw cap was 20 mm, the sample width was 15 mm, clamp pressure was 6 bar and the draw speed was 0.1 mm/s.
  • the tear strength of the films was determined according to the standard ISO 1974.
  • Example 1 (Comparative) - MFC film prepared by cast forming 20 or 30 gsm (g/m 2 ) films comprising 100% microfibrillated cellulose were prepared by dispersing a non-chemically modified microfibrillated cellulose in RO water to a consistency of 0.25 wt%. The suspension was then cast coated on a Petri dish in order to simulate a cast film forming process. The sample was dried in 23 °C / 50 % RH. The mechanical properties were determined for the 30 gsm films, and the barrier and optical properties were determined for the 20 gsm films. The results are presented in Table 2.
  • Example 2 10 % of Low PS (degree of substitution) phosphorylated pulp (p-pulp)
  • Non-chemically modified MFC and low DS p-pulp were weighed in a given ratio of 90/10 w/w and dispersed in RO water to a total consistency of 0.25 wt%.
  • a sample film was cast coated on a Petri dish as in Example 1. The results are presented in Table 2.
  • Example 3 20% of Low DS p-pulp Similar setup as in Example 2 but with 20% of low DS p-pulp.
  • Non-chemically modified MFC and low DS p-pulp were weighed in a given ratio of 80/20 w/w and dispersed in RO water to a total consistency of 0.25 wt%.
  • a sample film was cast coated on a Petri dish as in Example 1. The results are presented in Table 2.
  • the higher content of low DS p-pulp shows that transparency is improved and barrier properties on same level or even slightly lower compared to the reference (Example 1). A significant increase in tear strength was seen.
  • Example 4 10% of high PS o-oulo 10% of a high DS p-pulp was added to an MFC suspension prior to film formation.
  • Example 2 A sample film was cast coated on a Petri dish as in Example 1. The results are presented in Table 2. In particular, stretch was significantly improved when comparing to the reference (Example 1) and to the p-pulp having lower DS (Example 2).
  • Example 6 10% of DP (dissolving pulp) p-pulp 10% of a p-pulp made of dissolving pulp was added to an MFC suspension prior to film formation. A sample film was cast coated on a Petri dish as in Example 1. The results are presented in Table 2. The use of 10% p-pulp made from dissolving pulp resulted in a tear index comparative to the reference samples but the stretch was significantly higher.
  • DP dissolving pulp
  • Example 8 20% of a p-pulp made of dissolving pulp was added to an MFC suspension prior to film formation. A sample film was cast coated on a Petri dish as in Example 1. The results are presented in Table 2. The use of 20% p-pulp made from dissolving pulp resulted in a tear index comparative to the reference samples but the stretch was significantly higher. Also, the oxygen barrier properties (OTR) was significantly improved. The transparency or translucency was on same level as obtained when using 20% of the high DS p-pulp. Example 8 - 10% of unwashed p-pulp
  • the pulp was washed with RO water and filtrate analyzed after which the organic and ash content were determined. It was estimated that the total dissolved material content was about 40 wt%, whereas the ash content was 34 % when determined at 525 °C according to the standard ISO 1762.
  • the unwashed p-pulp refers to a Low DS pulp of Table 1 , but where the pulp was not washed after the reaction phosphorylation.
  • a sample film was cast coated on a Petri dish as in Example 1. The results are presented in Table 2. The film showed very low OTR value and high transmittance.
  • Example 10 (Comparative) - Reference film made with wet laid method
  • the same MFC as used in Example 1 was used.
  • the 20 and 30 gsm films were prepared using a vacuum dewatering method.
  • the chemically non- modified microfibrillated cellulose was dispersed in 0.1 wt% consistency.
  • the pH of the suspension was not adjusted.
  • Vacuum filtration was done using 0.65 pm DVPP filters as filtration media.
  • the films were couched and wet pressed prior to drum drying at 80 °C for 90 minutes.
  • the mechanical properties of the films were determined for the 30 gsm films, and the barrier and optical properties were determined for the 20 gsm films. The results are presented in Table 2.
  • Example 10 The same experimental setup as in Example 10 was used, but with a mixture of MFC and 10% low DS p-pulp as prepared in Example 2. The results are presented in Table 2. A small improvement in tear index was observed while, stretch and barrier decreased slightly as compared to the corresponding reference (Example 10).
  • Example 12 20% Low PS p-pulp
  • Example 3 The same experimental setup as in example 10 was used, but with a mixture of MFC and 20% low DS p-pulp as prepared in Example 3. The results are presented in Table 2. A small increase in tear index and better OTR oxygen barrier properties were observed as compared to the corresponding reference (Example 10).

Abstract

La présente invention concerne une composition de cellulose microfibrillée (MFC) pour la préparation de films ou de revêtements transparents ou translucides, ladite composition comprenant de la MFC à une concentration comprise entre 50 et 99,9 % en poids, et des fibres de cellulose phosphorylée à une concentration comprise entre 0,1 et 50 % en poids, sur la base du poids sec total de la composition de MFC. L'invention concerne en outre un film de MFC et un matériau multicouche comprenant la composition de MFC.
PCT/IB2020/059762 2019-10-17 2020-10-16 Composition de mfc avec des fibres de cellulose phosphorylées WO2021074879A1 (fr)

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SE545927C2 (en) * 2022-07-08 2024-03-19 Stora Enso Oyj A method for producing a paper or paperboard laminate
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2998435A1 (fr) * 2013-05-16 2016-03-23 Oji Holdings Corporation Fibres de cellulose estérifiée par l'acide phosphorique et leur procédé de fabrication
EP3483207A1 (fr) * 2016-07-08 2019-05-15 Oji Holdings Corporation Feuille
SE1900067A1 (en) * 2017-12-21 2019-06-22 Stora Enso Oyj A method for preparing a film of crosslinked microfibrillated cellulose
EP3521510A1 (fr) * 2016-09-30 2019-08-07 Oji Holdings Corporation Pâte, suspension, feuille, stratifié et procédé de fabrication de pâte

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2998435A1 (fr) * 2013-05-16 2016-03-23 Oji Holdings Corporation Fibres de cellulose estérifiée par l'acide phosphorique et leur procédé de fabrication
EP3483207A1 (fr) * 2016-07-08 2019-05-15 Oji Holdings Corporation Feuille
EP3521510A1 (fr) * 2016-09-30 2019-08-07 Oji Holdings Corporation Pâte, suspension, feuille, stratifié et procédé de fabrication de pâte
SE1900067A1 (en) * 2017-12-21 2019-06-22 Stora Enso Oyj A method for preparing a film of crosslinked microfibrillated cellulose

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